In a fascinating analysis, Gallup accesses movement in approval ratings for presidents as the memory of their time in office recedes: "[Our] review of
presidential job approval ratings finds that presidents' retrospective
approval ratings are almost always more positive than their job approval
ratings while in office. In particular, Americans rate John F. Kennedy,
Gerald Ford, Jimmy Carter, and Ronald Reagan much more positively in
retrospect than they did while the men were president." Here is Gallup's chart: